ColecoVision Video Upgrade Comparison Pictures

[doubledown]

Here's a few premlimenary pictures to show the clarity differences between different video upgrades on the ColecoVision/ADAM. The Luminance (brightness) on the VGA is a little high. I've got the VGA's prototype upgrade wired through an old adjustable resistance box I made a few years back and the potentiometers don't go high enough to compensate. It'll be rectified when I hard wire it, but you get the idea:

 

Zaxxon Title Screen - RF:

 

 

Zaxxon Title Screen - Composite Video:

 

 

Zaxxon Title Screen - VGA

 

 

Zaxxon Options Screen - RF:

 

 

Zaxxon Options Screen - Composite Video:

 

 

Zaxxon Options Screen - VGA:

 

 

Zaxxon In Game - RF:

 

 

Zaxxon In Game - Composite Video:

 

 

Zaxxon In Game - VGA:

 

 

I don't have the S-Video circuit in, and the Component Video circuit is what's feeding the VGA upscaller so that's why there's no pics of those upgrades yet. These pics were taken on my cheap-o ($200) Insignia 15" LCD monitor I use as my test display. Once I've got the ADAM completely done I'll get proper pics using a tripod for steadiness and I'll have pics of the RF, Composite Video, S-Video, Component Video, and VGA screens on a better large screen monitor. You can really see the differences in the text on the screens. I think VGA is the way to go. I'm sure the fact that the resolution is increased 2.5 times from 256 x 192 to 640 x 480 has something to do with it.

[Artlover]

Whoa!

 

Once the luminance issues on the VGA mod are worked out that thing is going be freaking AWESOME!

[Rik]

Goddamn! rf really sucks doesnt it!The difference is shocking,cant really notice it until they're side by side.Yeah,id say VGA is the way to go.Thanx for the comparion pics,i love those,keep up the great work,much appreciated!!!!

Edited August 17, 2008 by Rik

[doubledown]

I got the Luminance issue on the VGA fixed. It also helped to bring the yellow in a little better too as it was kind of washed out before. The camera can't really capture the colors properly as they're displayed on the screen, but the clarity difference is definately noticable. Here's a few pics of Montezuma's Revenge. There's a lot of detail with all the brick lines for comparison. Also look at Panama Joe in each of the 3 different pics. Notice his eye and shirt buttons for comparison.

 

RF:

 

 

Composite:

 

 

VGA:

 

[GonzoCV-1]

Hi Doubledown,

 

You're right that the whites and yellows on the composite look like they may be overdriven. Have you checked to see whether in a full saturation screen (e.g., explosion of the Gorf mothership, deployment of smart bomb in Defender, or explosion of death star in SW Arcade game, you wind up with overdrive of the TV/Video display?

 

You'll know if this is happenign on some LCD screens, as you'llget temporary screen blanking. On a TV, you'll get roll ever so briefly during full driving of the signal. A good test bed are those little Sony or Zenith PS1/XBOX portable screens. They have a very close to perfectly spec in tolerance composite in drive, and any signals that would look bad on an occilator will blank the screen as the circuit protects itself from an overdriven video signal.

 

 

I had the issue with wash out of yellow in the first few A/V mods I did to Colecovision, then I looked up the datasheet for the chip in the RF daughter circuit, and saw that it calls for a capacitor (presumably to remove the DC component), along with a 75 ohm resistor at the output stage after the video signal amplification transistor.

 

Try adding a 47uF 16v capacitor and 75 ohm resistor to your output stage and see if you can't get the "yellowish" yellow back in that opening screen, while also avoiding overdriving the signal. I'd guess you'll have to fine tune your amplification circuit, but I always get very satisfactory display with a variation of that sort. If you want to really be able to fine tune, use a 100 ohm pot as the impedance matching resistor, but set it to 75 ohms before installation as you'll only be tweaking slightly if at all once you get the voltage side of the amplifier where you want it.

 

You are obviously very good with these, so take this post as simply my perspective as I by no means mean to condescend. I just had exactly the problem with the colors you see and worked through it myself, so thought I'd offer the perspective of my experience.

[doubledown]

All of the pics are from an ADAM. The composite video signal is the standard output from the console not an additional circuit. Also the camera doesn't really capture the colors accurately for some reason.

[Artlover]

Also the camera doesn't really capture the colors accurately for some reason.

So orange does look orange on the VGA?

[GonzoCV-1]

All of the pics are from an ADAM. The composite video signal is the standard output from the console not an additional circuit. Also the camera doesn't really capture the colors accurately for some reason.

 

 

Thanks, and very interesting.

 

So the ADAM had a composite output integrated. I never had one, so I did not know that.

 

Is does the Adam run off the 9928A revision of the vid chip and mix luma and chroma diff in an RV mixer, taking composite from there; or does it use the 9918A version and just pull a composite off the video chip. (I am making a portable Colecovision currently, and I'm replacing the main VDP with the "9918" variant to allow me to discard the AV daughter board.

 

I can feel your pain on the camera issue. I've never been able to get great photos from a digital camera of a television screen output. That's one where high speed celluloid film off a tripod with a remote actuator still works best.

 

Cheers on your project. I'm looking forward to seeing how it turns out.

[doubledown]

With the Luminance corrected the colors look dead on accurate. The "ColecoVision" title screen is a good example due to the rainbow colors in the letter, but like I said the camera can't capture it properly.

 

The ADAM's VDP is the TMS9928ANL like the ColecoVision, and the composite video circuitry is in place in its stock form.

[Atariboy]

Using the Adam's composite output that it does in its stock form, I think on mine it almost rivals your VGA screenshot. I don't really see the need for modding it when for ten dollars you can just get the cable so you can get composite out and audio on the Adam.

 

I don't think I'd care for the lag, however small it may seem, that upscaling is going to add. I suppose if someone wants to play this on their hd sets, its a great mod. But for CRT's, I think the stock composite out looks awesome.

Edited August 18, 2008 by Atariboy

[doubledown]

The stock Composite is definately better than the RF, but again these photos of the screens aren't exactly perfect, you really need to see it in person. The VGA looks incredible in real life especially when compared to the Composite on an LCD screen. There is no lag at all with the upscaller. It would be noticable when playing, and everything on screen responds perfectly in sync with buttons pressed on the controller.